Brachycaudus persicae

Identification & Distribution:

Adult apterae of Brachycaudus persicae have a shiny sclerotized dark brown or black dorsum (see dark individual in first picture below). The fused apical rostral segments of the aptera are shorter than 0.175 mm in length. Their first tarsal segments are each with 2-3 hairs (cf. Brachycaudus schwartzi, which has the first tarsal segments each with 4 hairs). The flanged siphunculi are black (cf. Myzus persicae which have pale siphunculi with darkened tips) and are more than 0.1 times the body length, clearly more than twice the length of the cauda and longer than the hind tarsi (cf. Brachycaudus schwartzi, which has markedly shorter siphunculi). The cauda is dark, short and broad. The body length of adult apterae is 1.5-2.2 mm.

Micrographs of clarified mounts by permission of Roger Blackman, copyright AWP all rights reserved.

Brachycaudus persicae is most commonly found in large spring colonies on young stems of peach (Prunus persica) or apricot (Prunus armeniaca), often persisting into the summer on root suckers. In Europe there is some evidence of host alternation from Prunus to Orobanchaceae, but Brachycaudus persicae may remain all year on Prunus. Aphids apparently of this species are also widely distributed on peach outside Europe, including the Middle East, southern Africa, Australia, New Zealand, and North and South America.

Biology & Ecology:

We have only found Brachycaudus persicae on one occasion - on peach, nectarine and apricot in glasshouses at Hadlow College - where these pictures were taken.

There seems to be little published information on the ecology of Brachycaudus persicae either on its primary or secondary hosts. Secondary hosts are known to include Euphrasia, Melampyrum, and Rhinanthus where they live on the above-ground parts (Heie 1992).

Several types of natural enemy were present on the aphid colonies. A bright orange Entomopthora fungal pathogen (see above) was especially prevalent.

The dense aphid colonies produced abundant honeydew which attracted varous insects to feed on it such as the Chrysopa carnea adult shown below.

Other aphids on same host:

• Blackman & Eastop list 24 species of aphid as feeding on peach (Prunus persica) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 16 as occurring in Britain (Show British list).

• Blackman & Eastop list 21 species of aphid as feeding on apricot (Prunus armeniaca) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 13 as occurring in Britain (Show British list).

Damage and control

Heavy infestations of Brachycaudus persicae can be very damaging to host trees, especially in greenhouses. Shoots are distorted, growth is retarded, and young plants may be killed.

Shearer & Frecon (2002) investigated whether preplant root dips or postplant sprays or drenches could be used to control the black peach aphid on young peach trees. In greenhouse trials, Brachycaudus persicae died after being placed on peach trees that had their roots dipped in the insecticide imidacloprid before planting. All rates tested controlled this aphid. Approximately 50% of untreated trees died from Brachycaudus persicae infestations in greenhouse studies. Results from a field experiment show that peach trees root-dipped in imidacloprid before planting or drenched with imidacloprid after planting eliminate aphid infestations and prevent root colonization for at least a year.

Fos & Massonié (1993) showed in laboratory experiments that apterous and alate adults transmitted plum pox virus to seedlings of two peach cultivars. It was thought that the aphid might participate in the natural spread of plum pox diseases because it colonizes peach, apricot and plum orchards throughout the year.

Acknowledgements We especially thank Hadlow College for their kind assistance. Our particular thanks to Roger Blackman for images of his clarified slide mounts. Whilst we make every effort to ensure that identifications are correct, we cannot absolutely warranty their accuracy. We have mostly made identifications from high resolution photos of living specimens, along with host plant identity. In the great majority of cases, identifications have been confirmed by microscopic examination of preserved specimens. We have used the keys and species accounts of Blackman & Eastop (1994) and Blackman & Eastop (2006) supplemented with Blackman (1974), Stroyan (1977), Stroyan (1984), Blackman & Eastop (1984), Heie (1980-1995), Dixon & Thieme (2007) and Blackman (2010). We fully acknowledge these authors as the source for the (summarized) taxonomic information we have presented. Any errors in identification or information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure provided by Blackman & Eastop (2006).

Useful weblinks

References  Fos, A. & Massonié (1993). Transmission expérimentale du viruis de la sharka par Brachycaudus persicae Passerini. Agronomie 13 (6), 515-518. Abstract  Shearer, P.W. & Frecon, J.L. (2002). Managing Brachycaudus persicae (Homoptera: Aphididae) during peach orchard establishment. Journal of Economic Entomology 95 (2), 368-371. Abstract